S4 Pro Domin Direct Drive Servo Valve

Introducing the world’s smallest commercial Direct Drive Valve with On Board Electronics

Customise your valve to your specifications


The Domin S4 Pro delivers exceptional performance without the first stage leakage.

The S4 Pro redefines the art of the possible for a small servo valve. It represents the ultimate high performance miniature servo valve with built in electronic control. Domin have been able to combine the low leakage and high accuracy performance of a premium direct drive valve with the compact envelope of a traditional miniature two stage electro-hydraulic servo valve.

Rated Flow

Up to 18 lpm (at 70 Bar ∆P)

Maximum Flow

38 lpm

Frequency Response

> 350 Hz (-3 dB, up to +/-25 % FS)


< 0.1 %

Power Consumption

< 2 W at rated flow


< 265 g

Rotary to Rotary Valve Concept

The S4 Pro has been able to deliver it’s performance from the most simple of mechanical controls – a rotary control spool. A number of patents cover the features that have led to the design success of the S4 Pro. The control spool is directly coupled to a brushless motor with a precision rotary feedback transducer. A metallic membrane provides a fluid barrier separating the rotating elements of the valve from the electrical elements of motor and transducer. The configuration removes the need for rotary and internal high pressure seals.

Design enabled by the revolution of Additive Manufacturing

To solve the inherent challenges of the rotary to rotary valve concept, Domin engineers have used the full design freedom afforded by AM. It has resulted in a unique patented concept using a total of 16 fluid ports to perfectly balance the opposing pressure and flow forces within the valve. The result is a valve with the minimum of component parts incorporating complexity in two miniature AM components.

Innovation for Performance

Domin have been able to bring together the key benefits of a rotary motor drive and Additive Manufacturing to create an exciting blend of performance and size surpassing other servo valve technologies.

Low Power Consumption / High Dynamics

Domin has been able to achieve exceptional performance and low power consumption. It achieves a new industry benchmark in terms of bandwidth over the full operating range of amplitudes.

Low Internal Leakage

The valve employs Domin’s patented rotary valve technology to achieve exceptional dynamic performance with minimal internal leakage. The total on centre leakage for the axis cut valve is typically less than 1 % of maximum flow.

Unsurpassed Power to Weight

The 18 lpm version (@70 bar ∆P) weighs only 265 g and occupies a volume of less than 100 cc. It can achieve a bandwidth in excess of 350 Hz at up to 50 % input command.

Custom Configure to Your Specification

Our online configuration tool allows you to tailor each valve to your particular requirements. Flow-gain and valve lap condition can be set precisely to your needs using our unique sliding scale. Additionally, key interfaces can be chosen from a comprehensive range of alternatives.

Free delivery on all orders

Domin offer express shipping on standard valves

Pay Now

Buy straight from our online store for fast and efficient service

Bank Payment

Domin offer credit card or BACS transfer. Contact Domin to request payment on account

Need help with your order

Contact Domin for help with an order or for custom projects